The point about foliage efficiency is well taken, but even in densely spaced
plantations LAI is very important. For example, my casual observations
comparing poplar plantations in the Pacific NW vs. those in the Lakes States
and Northeast US indicate that the NW plantations carry far higher LAIs. The
differences in light levels, weed competition, etc. in our plantations vs.
yours in the NW is striking; even in bright sun it's very dark under the NW
plantations. I'm convinced that this high LAI is a major contributor to the
high productivity of NW plantations. Certainly we're talking different
clones, for the most part, but my understanding is that on the east side some
of the same clones that we plant back here have been used, but their canopies
sure do look different. The why questions associated with these observations
(if they in fact are true) would make for some interesting research.
Don